Adjustable wrenches having a head to which is attached a handle structure and incorporating a jaw structure that is disposed in movable, guided relation with the wrench head and is adjustable to accommodate different sizes of nuts, bolts and other flat sided objects are widely used in the industry. Although many different types of adjustable wrenches have been developed over the years, the most prevalent adjustable wrench being marketed at the present time is of the type incorporating a rotary worm gear in the wrench head structure which is disposed in driving relation with gear teeth that are provided on the movable jaw. Although these types of adjustable wrenches are quite well known, they have a number of disadvantages.
With the rotary worm gear drive located in the head structure of the wrench, it is necessary that the user accomplish rotation of the worm gear drive by rotating it with the thumb or finger while holding the wrench structure at or near the head portion thereof. If the nut or bolt to be rotated is located in an area that is accessible only by holding the handle portion of the wrench, then adjustment of the wrench jaw in this circumstance is typically accomplished by trial and error. Thus, it may take several trials and adjustments to properly position the movable jaw to rather tightly receive the opposed flat surface of a nut or bolt therebetween. Further, worm gear drive type adjustable wrenches are typically manufactured with quite wide tolerances in order to minimize the cost thereof. These wide tolerances typically permit the worm gear to have some degree of rotation while the wrench is being used. It is not unusual for movable jaw will spread from the fixed jaw of the head during use of the wrench, thereby requiring further adjustment in order to complete the task. Further, these wide tolerances of manufacture allow the wrench jaws to spread somewhat when force is applied by manual rotation of the wrench handle.
Even through the movable jaw of a conventional adjustable wrench may be properly adjusted for a close fit with the opposed flats of a nut or bolt, when force is applied upon manual rotation of the wrench handle about the nut or bolt, it is typical for the movable jaw to have some spreading movement due to the manufacturing tolerances of the jaw drive mechanism. When this occurs, engagement of the flat surfaces on the movable and fixed jaws of the wrench will often contact the nut or bolt head at or near the corners thereof such that a large force is applied to a very limited structural area of the nut or bolt. In this case, it is not unusual for the corners of the nut or bolt to become rounded as the structural integrity of the metal thereof is exceeded. Accordingly, it is desirable to provide an adjustable wrench mechanism that will have virtually no jaw movement upon application of manual force so that the nut, bolt or other object will be properly gripped between the flat surfaces of the movable and fixed jaws.
Also, it is desirable to provide an adjustable wrench mechanism that can be adjusted by manipulation of an adjustment mechanism provided at the end portion of the handle structure so that the jaw structure of the wrench may be properly adjusted to fit a remotely located nut or bolt without having to employ the typical trial and error approach that is ordinarily used.
Most wrenches are simply adjusted to the size of the nut or bolt to be rotated and do not provide any griping function at all. It is desirable to provide an adjustable wrench mechanism that has the capability of providing a tight gripping force on the nut, bolt, or other object. This feature would enable the wrench to also be employed as a clamping device to secure parts in temporary assembly. Further, even though a mechanism is employed to accomplish light gripping of a nut or bolt, it is desirable to ensure that the wrench mechanism is easily operable to release its tight gripping.